Revisiting annual screening for latent TB infection in healthcare workers: a cost-effectiveness analysis
Abstract
Background
In North America,
tuberculosis incidence is now very low and risk to healthcare
workers has fallen. Indeed, recent cohort data question routine
annual tuberculosis screening in this context. We compared the
cost-effectiveness of three potential strategies for ongoing
screening of North American healthcare workers at risk of
exposure. The analysis did not evaluate the cost-effectiveness
of screening at hiring, and considered only workers with
negative baseline tests.
Methods
A decision analysis model
simulated a hypothetical cohort of 1000 workers following
negative baseline tests, considering duties, tuberculosis
exposure, testing and treatment. Two tests were modelled, the
tuberculin skin test (TST) and QuantiFERON®-TB-Gold In-Tube
(QFT). Three screening strategies were compared: (1) annual
screening, where workers were tested yearly; (2) targeted
screening, where workers with high-risk duties (e.g. respiratory
therapy) were tested yearly and other workers only after
recognised exposure; and (3) post exposure-only screening, where
all workers were tested only after recognised exposure. Workers
with high-risk duties had 1% annual risk of infection, while
workers with standard patient care duties had 0.3%. In an
alternate higher-risk scenario, the corresponding annual risks
of infection were 3% and 1%, respectively. We projected costs,
morbidity, quality-adjusted survival and mortality over 20 years
after hiring. The analysis used the healthcare system
perspective and a 3% annual discount rate.
Results
Over 20 years, annual
screening with TST yielded an expected 2.68 active tuberculosis
cases/1000 workers, versus 2.83 for targeted screening and 3.03
for post-exposure screening only. In all cases, annual screening
was associated with poorer quality-adjusted survival, i.e. lost
quality-adjusted life years, compared to targeted or
post-exposure screening only. The annual TST screening strategy
yielded an incremental cost estimate of $1,717,539 per
additional case prevented versus targeted TST screening, which
in turn cost an incremental $426,678 per additional case
prevented versus post-exposure TST screening only. With the
alternate “higher-risk” scenario, the annual TST
strategy cost an estimated $426,678 per additional case
prevented versus the targeted TST strategy, which cost an
estimated $52,552 per additional case prevented versus
post-exposure TST screening only. In all cases, QFT was more
expensive than TST, with no or limited added benefit.
Sensitivity analysis suggested that, even with limited exposure
recognition, annual screening was poorly cost-effective.
Conclusions
For most North American
healthcare workers, annual tuberculosis screening appears poorly
cost-effective. Reconsideration of screening practices is
warranted.
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Source:
BMC Medicine
